Population of Portland proper has actually grown substantially, >= 7% in the last 10 years or so. The entire metro area may have increased even more, I'm not sure about that. Portland State University maintains a demographic study center with the data but I didn't check there for this comment.
The necessity for constructing more housing units isn't questioned, but there's a lot of discussion about projects that the city planners allowed to exceed the originally planned height restrictions without the issue being open for community input. The lack of procedural transparency in these cases has evoked the ire of concerned citizens.
As far as neighborhoods go, close-in areas have experienced marked "gentrification", displacing lower income populations to the "high number" districts of east Portland where housing is less expensive. So indeed development has had substantial effects on some neighborhoods, whether that's "good" or "bad" can be debated, but it is a reality.